INSKEEP: The Democrat says he has not decided how to vote, but he needs the president to win over his Maryland constituents. We've heard many voices in this debate all week, and now Tony Blinken is on the line. He is the president's deputy national security advisor.

Welcome to the program, sir.

TONY BLINKEN: Steve, thanks for having me.

INSKEEP: OK, so we've heard the president's case on chemical weapons in Syria. We've heard people raise concerns about a military strike. And I want to just go directly to some follow-up questions, here, like, give you a chance to answer some specific concerns that people have raised.

Joe Manchin, Democratic senator, West Virginia, says he's against using force. He says we must exhaust all diplomatic options before acting. Have you exhausted the diplomatic options?

BLINKEN: You know, I'm very sympathetic to what Senator Manchin said, but I think the fact is we have. We have imposed severe sanctions on Syria and on the Assad regime. We've squeezed and squeezed and squeezed. More to the point: We've gone repeatedly to the United Nations, to the Security Council, trying to get the Security Council to act on much lesser things, just to criticize and condemn what was going on in Syria, the civil war, the conflict, the violence being perpetrated by the Assad regime. Time and again, almost a dozen times, we've been blocked in the Security Council.

So, at this point, we unfortunately have exhausted everything. And, in that context, to have this horrific chemical weapons attack that took well over a thousand lives, including hundreds of children, for that to go unanswered would lead to even worse things.

INSKEEP: Manchin is also saying that you need a comprehensive plan for international involvement before acting. Have you really done everything you can do to line up allies, here?

BLINKEN: You know, as we speak, the president is in Europe, working with the G-20 and working to build that international support. Secretary Kerry is heading this weekend to Europe, where he'll see Europeans and Arabs. Country by country, at the United Nations, here in Washington, we're reaching out to build support. And I believe we're getting it. We're seeing dozens of countries directly criticizing the Assad regime, pointing out that the use of chemical weapons is unacceptable, and an increasing number saying that something needs to be done about it.

INSKEEP: I want to ask about another concern that's been raised in different ways, a concern about a wider war, the reality that the enemy has a vote. There could be a response. Something could happen beyond what you're promising, here. If people, in the end, in Congress vote yes with you, should the country be mentally prepared for a wider war?

BLINKEN: No. And, Steve, let me tell you what I think is going on, here, and it's very understandable. When people hear about the prospect of military conflict in Syria, when they hear about the potential use of military force in Syria, the prism through which they process that is the last decade. They're thinking about Iraq. They're thinking about Afghanistan. They're thinking about 150,000 American troops in one, 100,000 in another.

So it's very important for people to understand what this is and what this isn't. What this is is a very targeted, very focused, but we believe effective use of force to deal with the fact that chemical weapons were used, and to try to make sure that Assad doesn't use them again, or that it's more difficult for him to use them again if he tries.

INSKEEP: And you're sure...

BLINKEN: What it's not is boots-on-the-ground. What it's not is open-ended. What it's not is Iraq, Afghanistan, or even what we saw in Libya.

INSKEEP: And you're sure that Iran won't respond, that Syria can't respond? That Hezbollah and other groups will not respond to this?

BLINKEN: Steve, we spend a lot of time when we think about these things trying to game out every possible contingency, every possible unintended consequence. And no one can give you 100 percent guarantee. But we work to mitigate. We work to make sure that if anyone tries to do anything to escalate, we're in a position to respond. But our best assessment - including by our intelligence community - is that none of these countries have an incentive to pick a fight with the United States.

INSKEEP: One quick question before we go away, Tony Blinken. Has the president decided what he will do if Congress votes no on using force?

BLINKEN: You know, Steve, when - after the events of August 21st, we reached out to Congress, and we had conversations with members of Congress across the country. And the one thing we heard from nearly all of them was that they wanted their voice heard and their vote counted in this.

INSKEEP: Just a couple seconds, here. Will he strike?

BLINKEN: And the president, of course, has the authority to act, but it's neither his desire nor his intention to use that authority absent Congress backing him.